Lake Manitoba and its Watershed: Knowledge Gaps & Next Steps Sunrise over Lake Manitoba at Delta Marsh (© Marliese Peterson) TABLE OF CONTENTS 1. Executive Summary ................................................................................................................. 1 2. Introduction.............................................................................................................................. 2 2.1. Background to Lake Manitoba .......................................................................................... 2 2.2. Rationale for workshop ..................................................................................................... 2 3. Water Levels & Regulation..................................................................................................... 4 3.1. Presentations ..................................................................................................................... 4 3.2. Knowledge Gaps ............................................................................................................... 4 3.1. Next Steps For Top-Ranked Knowledge Gaps ................................................................. 8 4. Watershed Management & Landscape Processes .............................................................. 12 4.1. Presentations ................................................................................................................... 12 4.2. Knowledge Gaps ............................................................................................................. 12 4.3. Next Steps for Top Ranked Knowledge Gaps ................................................................ 16 5. Water Quality ......................................................................................................................... 19 5.1. Presentations ................................................................................................................... 19 5.2. Knowledge Gaps ............................................................................................................. 20 5.3. Next Steps for Top Ranked Knowledge Gaps ................................................................ 24 6. Ecology & Wetlands .............................................................................................................. 26 6.1. Presentations ................................................................................................................... 26 6.2. Knowledge Gaps ............................................................................................................. 26 6.3. Next Steps for Top Ranked Knowledge Gaps ................................................................ 30 7. Conclusions ............................................................................................................................. 32 8. Acknowledgements ................................................................................................................ 33 Appendix A: List of Participants................................................................................................ 34 Appendix B: Abstracts ................................................................................................................ 35 Workshop on Lake Manitoba and its Watershed – Executive Summary 1. EXECUTIVE SUMMARY Lake Manitoba is a large, shallow prairie lake located in central Manitoba. The lake and watershed are subject to numerous environmental pressures including climate change, land use change, and regulation of water levels, particularly during the operation of the Portage Diversion which diverts water from the Assiniboine River into Lake Manitoba. There are substantial gaps in our scientific knowledge about the ecology, limnology, and hydrology of Lake Manitoba, which limit our ability to make informed management decisions. A science workshop was convened at the University of Winnipeg in December 2015 to summarize the state of knowledge around water quality and ecosystem functioning in Lake Manitoba and its watershed, identify key knowledge gaps, and develop ways to address these gaps. The workshop was attended by 34 participants from universities, government agencies, and non- governmental organizations, all of whom had particular expertise in one of four theme areas: Water Levels & Regulation; Watershed Management & Landscape Processes; Water Quality; and Ecology & Wetlands. This report summarizes the findings and recommendations of the workshop, and can be used to help guide research priorities into the future. While specific, detailed recommendations were made in each theme area, two major recommendations emerged across all themes. The first recommendation is the existence of critical data gaps which must be filled before progress can be made on understanding ecosystem functioning. These gaps include physical data (e.g. bathymetric, meteorological and LiDAR data), water quality data (e.g. off-shore water chemistry, tributary nutrient loading), and ecological data (e.g. algal community composition, zooplankton characterization, macroinvertebrates population estimates). Furthermore, we do not understand the extent of spatial and temporal heterogeneity in the Lake Manitoba system. Much of the monitoring that does take place occurs along the edges of the lake during the open water season, resulting in large gaps in our understanding of processes occurring in the middle of the lake or during the winter. Without filling these critical data gaps, our scientific understanding of the system is incomplete and we are limited in our ability to make recommendations to resource managers and stakeholders. The second general recommendation that emerged is the need to coordinate research activities across disciplines and agencies. Lake Manitoba and its watershed are complex ecosystems which are connected to the landscape and other waterbodies, including Lakes Winnipeg and Winnipegosis. To this end, we propose establishing a Manitoba Great Lakes Research Consortium to coordinate and disseminate research across Manitoba’s Great Lakes. Such an organization could also facilitate a repository to make data collected from Lake Manitoba and connected ecosystems accessible to researchers and stakeholders. While there are major gaps in our understanding of ecosystem functions in Lake Manitoba and its watershed, this report provides a way forward. For the gaps that were identified as the most pressing, workshop participants outlined plans of action to address these gaps, including identifying collaborators, potential sources of funding, and timelines to achieve these goals. These next steps will be useful to researchers, government agencies, and non-governmental organizations as they move forward to address the issues facing Lake Manitoba. 1 Workshop on Lake Manitoba and its Watershed – Introduction 2. INTRODUCTION 2.1. BACKGROUND TO LAKE MANITOBA Lake Manitoba is a large (13th largest lake in North America), shallow (maximum depth = 7 metres) lake located in central Manitoba, Canada (Figure 1). Lake Manitoba is subject to many of the same environmental pressures as other prairie lakes, such as Lake Winnipeg, including land use changes in the watershed, hydrological changes due to water level regulation, and climate change. There are unique pressures on Lake Manitoba as well, including the operation of the Portage Diversion during high-flow events, which introduces water, sediment, and nutrients from outside the natural watershed into the lake. The Lake Manitoba basin contributes to nutrient loading in Lake Winnipeg, and alterations to the nutrient status of Lake Manitoba have the potential to impact the water quality and ecosystem health of Lake Winnipeg. While there is some monitoring of water quality and other ecosystem parameters in Lake Manitoba and its watershed, there are substantial gaps in our understanding of how this ecological system functions, which limits our ability to make informed management decisions moving into the future. For more information on Lake Manitoba, see Gord Goldsborough – A review of the limnology of Lake Manitoba: A large, shallow lake in south-central Canada (p. 35). 2.2. RATIONALE FOR WORKSHOP The goal of this workshop was to assess the current state of knowledge of water quality and ecosystem health issues in Lake Manitoba and its watershed, identify critical knowledge gaps, and brainstorm ways to address these gaps. The workshop was held from December 9-11th 2015 at the University of Winnipeg. It was attended by 34 participants from universities, provincial and federal government agencies, and non-governmental organizations (Appendix A, p. 34). Presentations and discussions at the workshop were divided into 4 major themes: 1) Water Levels and Regulation (p. 4) 2) Watershed Management and Landscape Processes (p. 12) 3) Water Quality (p. 19) 4) Ecology and Wetlands (p. 26) Each session of the workshop began with presentations from researchers who had worked in Lake Manitoba or similar systems. Abstracts for each of the presentations are found in Appendix B of this report (p. 35). Following each round of presentations, small group discussions were focused around identifying knowledge gaps related to the theme. These knowledge gaps were ultimately combined into one list per theme, and the whole group voted on which knowledge gaps were most important. Ranking of knowledge gaps was done based on personal criteria, including considerations such as priority relative to other gaps, feasibility of addressing